Seat belt mounted air bag puncture device

ABSTRACT

An air bag puncture device extends from the torso of a vehicle occupant and has a pointed outer end. Upon inflation of an air bag against the torso of the occupant, the device punctures the air bag to soften the outer surface of the air bag and thereby prevent injury to the occupant. The puncture device is mounted on a resilient clip for removable mounting to the shoulder harness of a vehicle seat belt system and comprises a cylindrical cutting device having a serrated outer end opposite the resilient clip for puncturing the inflating air bag. A hollow cylindrical collar is sidably mounted on the cylindrical cutting device and normally extends beyond the serrated outer end of the cutting device to prevent unwanted injury to the vehicle occupants. However, upon inflation of the air bag, the bag pushes the hollow cylindrical collar along the cutting device, against the resistance of a coil spring disposed between the hollow cylindrical collar and the resilient clip, until the serrated outer end of the cutting device protrudes from the cylindrical collar and punctures the air bag so as provide a controlled amount of deflation of the air bag. The coil spring defines a predetermined amount of force by the inflating bag which is necessary before the bag is punctured. As the bag is punctured, escaping gas therefrom is vented through the hollow interior of the cutting device and out through a venting slot in the cutting device and a vent hole in the cylindrical collar.

BACKGROUND OF THE INVENTION

1. Area of the Art

The present invention relates to vehicle safety devices, and moreparticularly to a device which punctures an inflating air bag incontrolled fashion so as to soften the surface of the inflating air bagand prevent injury to the vehicle occupant.

1. Description of the Prior Art

It is known in the art to provide arrangements for venting an inflatingair bag to prevent injury to the vehicle occupant. Examples of suchinclude U.S. Pat. No. 5,603,526 of Buchanan in which an air bag cushionhas frangible vent coverings and vent openings which permit inflationgas to exit the cushion and provide the proper pressure reduction forpreventing injury to the passenger. In U.S. Pat. No. 5,725,244 ofCundill, an air bag has a venting mechanism that allows inflation gas tovent from an inflation chamber through an expandable venting member.When the inflation pressure in the air bag reaches a preselected level,the frangible portion of the retaining member breaks and the ventingmember is expanded through the broken portion allowing the inflation gasto vent to the atmosphere.

Still other arrangements known in the art combine with a vehicle seatbelt system to protect the vehicle occupant from injury. In U.S. Pat.No. 6,273,467 of Berke et al., a surgical shield mounted on the shoulderstrap of the seat belt system prevents rubbing of the strip on asensitive or physically impaired body area such as a heart pacer, chestinjuries, or the like. U.S. Pat. No. 6,439,333 of Domens et al.describes a sensor system for inflating an air bag in a differentiatedway. The position of the vehicle occupant is determined by using theseat belt as an active reference position. The distance between the seatbelt and known points within the vehicle determines the position of theseat belt and thus the vehicle occupant. U.S. Pat. No. 6,557,895 ofHaack et al. describes a protective pad similar to that described inU.S. Pat. No. 6,273,467 of Berke et al. Similarly, U.S. Pat. No.6,576,808 of Dreyer describes a protective device for a sensitive orvulnerable area of the chest of the seat belt wearer.

SUMMARY OF THE INVENTION

The present invention provides an air bag puncture device for controlleddeflation of an inflating air bag. The puncture device comprises anelement having at least one sharp point and an arrangement for mountingthe device so that the at least one sharp point extends outwardly fromthe torso of a vehicle occupant and punctures an air bag upon inflationonto the torso of the occupant. The arrangement for mounting the devicemay include a vehicle seat belt and means for mounting the device on theseat belt. The device may include a clip for removably mounting thedevice on the seat belt.

The puncture device may include means for venting gas from the inflatingair bag upon puncturing of the bag. The puncture device may also includeapparatus for shielding the pointed tip except when the air bag inflatesagainst the puncture device. The shielding apparatus is operative toshield the sharp point until an air bag inflates against the puncturedevice with a predetermined force.

In a preferred embodiment of an air bag puncture device according to theinvention, a cylindrical cutting device has a serrated outer end and anopposite inner end mounted on a resilient clip for removably mountingthe device on a vehicle seat belt. A spring loaded collar is slidablymounted on the cylindrical cutting device and includes a spring having aresilient resistance to sliding movement of the collar over the cuttingdevice so as to define a predetermined amount of force exerted by aninflating air bag before the bag is punctured. Venting of gas from aninflating air bag upon puncturing of the bag is facilitated by a ventingslot in the cylindrical cutting device and a vent hole in the springloaded collar.

DESCRIPTION OF THE FIGURES

FIG. 1 is a front view of a vehicle occupant restrained by a shoulderbelt having an air bag puncture device mounted thereon in accordancewith the invention.

FIG. 2 is a perspective view of the air bag puncture device of FIG. 1.

FIG. 3 is an exploded perspective view of a portion of the air bagpuncture device of FIG. 2 showing a venting slot and vent hole forventing escaping gas from a punctured air bag.

FIG. 4 is a side view of a portion of the air bag puncture device ofFIG. 2 showing the manner in which a spring loaded collar normallyshields a serrated outer end of a cylindrical cutting device.

FIG. 5 is a side view similar to that of FIG. 4 but showing the mannerin which an inflating air bag overcomes the resistance of the springloaded collar so that the serrated outer end of the cutting device isable to puncture the inflating air bag.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a representation of a vehicle occupant 10 wearing a seat beltsystem 12. Only a shoulder harness 14 of the seat belt system 12 isshown, inasmuch as that is the portion of the seat belt system 12 whichextends across the torso 16 of the vehicle occupant 10. The shoulderharness 14 represents that of a driver of the vehicle, but the inventionis equally applicable to passengers as well. The invention is applicableto any vehicle occupant who is protected by an air bag.

As shown in FIG. 1, an air bag puncture device 18 in accordance with theinvention is mounted on the shoulder harness 14. This is a convenientway of mounting the air bag puncture device 18 so that it extends fromthe torso 16 of the occupant 10. As described hereafter, the air bagpuncture device 18 is removably mounted on the shoulder harness 14.However, other mounting arrangements can be used, so long as the air bagpuncture device 18 is mounted in the region of the torso 16 of thevehicle occupant 10 where it can engage and puncture an air bag uponinflation of the air bag into the vehicle occupant 10.

As shown in FIG. 2, the air bag puncture device 18 is made removable byuse of a resilient clip 20. The clip 20 has opposite facing portions 22and 24 which are resiliently biased together. To mount the clip 20 onthe shoulder harness 14, it is only necessary to separate the portions22 and 24 against the resilient resistance of the clip 20 and slide theportions 22 and 24 over opposite sides of the shoulder harness 14. Onceinstalled on the shoulder harness 14 in this fashion, the resilience ofthe clip 20 holds it in place.

The air bag puncture device 18 includes a cylindrical cutting device 26which is best shown in FIG. 3. The cutting device 26 is of hollowcylindrical configuration and has a serrated outer end 28 whichterminates in a circular array of sharp points. The cutting device 26has an end 30 opposite the outer end 28 which is mounted on the portion22 of the resilient clip 20.

The air bag puncture device 18 has a spring loaded collar assembly 32which includes a hollow cylindrical collar 34 having a coil spring 36coupled to one end thereof. The cylindrical collar 34 is mounted forsliding movement along the outside of the cutting device 26. The coilspring 36 is also disposed around the outside of the cutting device 26and extends between an inner end 38 of the cylindrical collar 34 and theportion 22 of the clip 20.

As shown in FIG. 3, the air bag puncture device 18 has a ventingarrangement for venting gas when an air bag is punctured, as describedhereafter. The venting arrangement includes a venting slot 40 in a lowerside of the cutting device 26, and a vent hole 42 in a lower side of thecylindrical collar 34.

FIG. 4 shows the normal orientation of the air bag puncture device 18when an air bag has not been deployed. To shield the vehicle occupant 10and others from the sharp points of the serrated outer end 28 of thecutting device 26, the cylindrical collar 34 extends beyond the serratedouter end 28 so that an outer end 44 thereof is outside of the serratedouter end 28.

FIG. 5 illustrates the manner in which the air bag puncture device 18punctures an inflating air bag 46. As the air bag 46 inflates, itextends outwardly and into the region of the torso 16 of the vehicleoccupant 10. It is well documented that vehicle air bags act to protectthe vehicle occupants from serious injury. At the same time, however,the outer surface and other outer portions of the air bag tend topresent a relatively hard outer surface of the air bag which can lead tofacial and other bodily abrasions and other injuries. This occursbecause the air bag inflates rapidly and with considerable force andpresents a hard surface to the vehicle occupant 10 for a brief moment.

In accordance with the invention, the air bag puncture device 18 acts topuncture and partially deflate the inflating air bag 42 as it reachesthe vehicle occupant 10. As a result, the outer portions of theinflating air bag 46 are greatly softened so as to minimize injury tothe occupant 10. As the air bag 46 inflates, it strikes the outer end 40of the cylindrical collar 34. Thereafter, the collar 34 slides along thecutting device 26 against the resistance of the coil spring 36.Eventually, the collar 34 reaches the position shown in FIG. 5 in whichthe serrated outer end 28 of the cutting device 26 protrudes beyond theouter end 40 of the collar 34 and punctures the surface of the air bag46. When this occurs, the air bag 46 begins to deflate.

To accommodate escaping gases from the deflating air bag 46, such gasesflow into the hollow interior of the cutting device 26. From there, suchgases flow through the venting slot 40 of the cutting device 26 andthrough the vent hole 42 in the cylindrical collar 34 to the outside ofthe air bag puncture device 18.

The inflating air bag 46 must overcome the resistance of the coil spring36 so that the cylindrical collar 34 is pushed back to expose theserrated outer end 28 before the air bag 46 is punctured. The forceneeded to overcome the resistance of the coil spring 36 is predictableand provides the air bag puncture device 18 with a predetermined forcecharacteristic for puncturing the air bag 46. This is important to thesuccessful operation of the air bag puncture device 18. Prematurepuncturing of the air bag 46 can result in a reduction in the overalleffectiveness of the air bag 46. On the other hand, delayed puncturingof the air bag 46 as the result of too much force being needed toovercome the resistance of the coil spring 36 can result in the vehicleoccupant 10 being struck by a hard outer surface of the air bag 46 andpossibly sustaining injury. Puncturing of the air bag 46 at the rightmoment and by the desired amount allows the air bag 46 to maintain itsoverall effectiveness while at the same time softening the outer severalinches of the air bag 46 so as to minimize or eliminate injury fromengagement with the normally hard outer surface of the air bag 46.

It will be understood that air bag puncture devices in accordance withthe invention can take on forms other than that shown and describedherein while still achieving the advantages of the invention. Theimportant consideration is that a pointed object be located at or inproximity to the torso of the vehicle occupant where the air bag comesin contact with the occupant upon deployment. Apart from that, featuressuch as the known spring resistance and the venting effect provided bythe particular embodiment of the air bag puncture device 18 disclosedherein can be employed to optimize the performance of air bag puncturedevices according to the invention.

1. A seat belt system for controlled deflation of an inflating air bagcomprising a belt for disposition on a vehicle occupant and a puncturedevice mounted on the belt and having a pointed tip for puncturing anair bag which inflates against the belt.
 2. A seat belt system accordingto claim 1, wherein the puncture device includes means for venting gasfrom an inflating air bag upon puncturing of the bag.
 3. A seat beltsystem according to claim 1, wherein the puncture device includes a clipfor removably mounting the device on the belt.
 4. A seat belt systemaccording to claim 1, wherein the puncture device includes means forshielding the pointed tip except when an air bag inflates against thebelt.
 5. A seat belt system according to claim 4, wherein the means forshielding is operative to shield the pointed tip until an air baginflates against the belt with a predetermined force.
 6. A seat beltsystem according to claim 5, wherein the means for shielding includes ashielding element slidably mounted on the puncture device and aresilient element coupled to the shielding element.
 7. An air bagpuncture device comprising an element having at least one sharp pointand an arrangement for mounting the device so that the at least onesharp point extends outwardly from the torso of a vehicle occupant andpunctures an air bag upon inflation onto the torso of the occupant. 8.An air bag puncture device according to claim 7, wherein the arrangementfor mounting the device includes a vehicle seat belt and means formounting the device on the seat belt.
 9. An air bag puncture devicecomprising a cylindrical cutting device having a serrated outer end, aspring loaded collar slidably mounted on the cylindrical cutting deviceand means for mounting the cylindrical cutting device on a vehicle seatbelt.
 10. An air bag puncture device according to claim 9, wherein thespring loaded collar includes a spring having a resilient resistance tosliding movement of the collar over the cutting device which defines apredetermined amount of force necessary for the cutting device topuncture an inflating air bag.
 11. An air bag puncture device accordingto claim 9, wherein the cylindrical cutting device has a venting slottherein, and the spring loaded collar has a vent hole therein.
 12. Anair bag puncture device according to claim 9, wherein the puncturedevice includes means for removably mounting the cylindrical cuttingdevice on a vehicle seat belt.
 13. An air bag puncture device accordingto claim 12, wherein the means for removably mounting includes aresilient clip.
 14. An air bag puncture device according to claim 13,wherein the cylindrical cutting device has an inner end opposite theserrated outer end which is mounted on the resilient clip and the springloaded collar includes a hollow cylindrical collar slidably mounted onthe cylindrical cutting device and a coil spring disposed about theoutside of the cylindrical cutting device and extending between an endof the collar and the resilient clip.